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Bowel cancer screening, FIT, colonoscopy and CT colonography - the modern menu for detecting cancer early.

Bowel (colorectal) cancer is the fourth most common UK cancer - and highly treatable if caught early. Modern screening: FIT (faecal immunochemical test) from age 50–74 on the NHS, private colonoscopy or CT colonography, and earlier or higher-frequency screening for high-risk groups.

A consultant gastroenterologist reviewing a bowel cancer screening pathway in a private London clinic

Key facts

  • Definition

    Asymptomatic screening for bowel cancer and pre-cancerous polyps.

  • NHS FIT

    Home stool test every 2 years, ages 50–74.

  • Positive FIT

    Triggers a diagnostic colonoscopy.

  • Gold standard

    Private colonoscopy is the definitive diagnostic test.

  • CT colonography

    A good alternative for frail patients or when colonoscopy is incomplete.

  • High-risk groups

    Earlier or more frequent screening for family history and Lynch syndrome.

Indicative pricing

What private bowel cancer screening costs in London.

Indicative ranges across UK private providers.

In short

£1,800–£3,200, with findings the same day.

Test type Indicative range
FIT (faecal immunochemical test) NHS free · Private £50–£120
Diagnostic colonoscopy (private) £1,800–£3,200
Colonoscopy + polypectomy £2,200–£4,000
CT colonography £900–£1,600
Gastroenterology consult + FIT + colonoscopy package £2,400–£4,500
Genetic testing (Lynch / FAP panel) £400–£1,200

Prices vary by clinic, whether polypectomy is performed and whether a consultant gastroenterology consultation is included.

The problem

Bowel cancer is one of the most preventable cancers - if you screen.

The NHS FIT programme catches many cases, but plenty of people are missed - those under 50, those with a family history, those who never returned the kit. Private screening fills the gap.

  • Family history worrying you?

    We tailor the interval and modality to your inherited risk, with genetic testing if indicated.

  • Positive FIT and long NHS wait?

    We escalate to a private diagnostic colonoscopy without losing the NHS pathway.

What it shows

What bowel cancer screening picks up.

Screening finds pre-cancerous polyps and early cancer, and often flags incidental colonic disease. Here is the spectrum.

  • FIT positive result

    A raised faecal haemoglobin - the trigger for onward colonoscopy.

  • Colonic polyps (adenoma, serrated)

    Pre-cancerous lesions found and removed at colonoscopy.

  • High-grade dysplasia

    Severely abnormal cells within a polyp - one step short of cancer.

  • Colorectal cancer

    The disease the whole programme is designed to catch early.

  • Diverticular disease

    Small outpouchings of the colonic wall - common and usually incidental.

  • Angiodysplasia

    Abnormal small vessels - a cause of iron-deficiency anaemia.

  • Inflammatory bowel disease

    Crohn’s or ulcerative colitis first picked up on screening endoscopy.

  • Red flag: cancer or high-grade lesion - two-week wait pathway

    We route you straight into an urgent MDT pathway, not a delayed private slot.

Red flags

When it isn’t screening - it’s a two-week-wait pathway.

If any of these apply, you need urgent diagnostic assessment, not asymptomatic screening. Speak to your GP the same day.

  • Rectal bleeding

  • Iron deficiency anaemia

  • Change in bowel habit > 6 weeks

  • Unintentional weight loss

  • Palpable abdominal or rectal mass

  • Colorectal cancer under 50 (young-onset)

  • Lynch syndrome family history

  • Familial adenomatous polyposis

  • Inflammatory bowel disease with dysplasia

Test types

Not all bowel screening is the same.

What each option on your pathway is actually for.

  • FIT (faecal immunochemical test)

    A quantitative stool test for haemoglobin - the NHS screening backbone, ages 50–74.

  • Diagnostic colonoscopy

    Direct endoscopic inspection of the entire colon and terminal ileum - the gold standard.

  • Colonoscopy + polypectomy

    Same procedure, with removal of any polyp found in the same sitting.

  • CT colonography

    A CT-based virtual colonoscopy - a good alternative for frail patients or after incomplete colonoscopy.

  • Flexible sigmoidoscopy

    Endoscopic assessment of the left colon - useful when the concern is distal.

  • Capsule endoscopy

    Swallowed pill camera - occasionally used when standard endoscopy has failed.

  • Genetic testing (Lynch / FAP)

    Blood-based panel for the two most common inherited colorectal cancer syndromes.

  • Surveillance colonoscopy

    Repeat endoscopy at an interval based on polyp size, number and histology.

Safety and eligibility

A very safe test - with a few real considerations.

FIT is risk-free. Colonoscopy is safe but not zero-risk - here is what to know before you book.

  • FIT is a safe home test

    No preparation, no risk - a single stool sample, returned by post.

  • Colonoscopy is a day-case

    Sedation, procedure and recovery in the same visit - home the same day with a chaperone.

  • Bowel prep is the hardest part

    Two doses of a laxative solution the day before - inconvenient, not dangerous. Stay near a toilet.

  • Perforation risk is low

    Approximately 1 in 1,000 diagnostic colonoscopies; higher when polypectomy is performed.

  • Bleeding after polypectomy

    Minor bleeding is common and self-limiting; significant bleeding is uncommon.

  • CT colonography uses radiation

    A low-dose CT - appropriate when colonoscopy is contraindicated or has failed.

  • Not for acute symptoms

    Rectal bleeding or a change in bowel habit is a two-week-wait pathway, not screening.

  • Bring prior imaging and reports

    Previous colonoscopy reports and histology materially sharpen surveillance intervals.

Reading your report

A colonoscopy report can look intimidating. It isn’t.

Whatever the finding, the report keeps to the same four parts.

A consultant gastroenterologist reviewing colonoscopy images on a clinical workstation at a UK private clinic

A quiet reminder

The report is written for your doctor, not for you - and that’s normal.

If you would like us to talk you through it before your follow-up, just ask.

  1. 01 Header

    Indication and risk factors

    Symptoms, family history, previous polyps and the reason for the procedure.

  2. 02 Technique

    Extent, prep quality, withdrawal time

    How far the scope reached, the Boston bowel prep score and the withdrawal time - quality markers that matter.

  3. 03 Findings

    Polyps, lesions, biopsy sites

    Vessel-by-vessel description with the Paris and NICE classifications, and where biopsies were taken.

  4. 04 Impression

    The plan: surveillance interval or MDT

    Normal, polyps removed with a surveillance interval, or a cancer pathway - read this first.

Treatment and next steps

What happens after your result.

The result shapes the plan - from reassurance to polypectomy to a full MDT pathway.

  • Reassurance if all negative

    A clear result with a repeat interval based on your risk.

  • Polypectomy during colonoscopy

    Most polyps are removed in the same sitting - no second procedure needed.

  • EMR / ESD for larger lesions

    Endoscopic mucosal or submucosal resection for polyps too large for standard snare.

  • Colorectal surgery for cancer

    Consultant colorectal surgery, laparoscopic or open depending on stage and site.

  • Neoadjuvant chemoradiotherapy (rectal cancer)

    Shrinking the tumour before surgery - the standard for locally advanced rectal cancer.

  • Genetic testing for Lynch syndrome / FAP

    Blood-based panel for inherited syndromes, especially in young-onset or strong family history.

  • Surveillance interval based on polyps

    BSG guidance dictates the next colonoscopy at 3, 5 or 10 years.

  • Family-cascade screening

    Screening for first-degree relatives when a syndrome or early cancer is confirmed.

Recognised by major UK insurers

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Frequently asked

Everything we get asked about bowel cancer screening.

Quick answers on FIT, cost, family history, CT colonography and when a symptomatic pathway is the right route instead.

  • What is bowel cancer screening?

    A programme of asymptomatic testing to find bowel (colorectal) cancer and pre-cancerous polyps early. The NHS offers a home FIT test every two years for ages 50–74; private options add colonoscopy and CT colonography.

  • What is the FIT test?

    The faecal immunochemical test - a quantitative stool test for human haemoglobin. A single sample, collected at home and returned by post. A positive result triggers a diagnostic colonoscopy.

  • Is a private colonoscopy worth it?

    Colonoscopy is the gold-standard diagnostic test - it visualises the entire colon and removes polyps on the spot. Private routes offer earlier slots, choice of consultant and a package price. It is not a replacement for the NHS FIT screening programme, but a legitimate step for symptomatic patients or those wanting definitive screening.

  • What is CT colonography, and when is it used?

    A CT scan of the colon after bowel prep and gas insufflation - a virtual colonoscopy. It is a good alternative for frail patients, when colonoscopy is incomplete, or when sedation is undesirable. It cannot remove polyps.

  • What if I have a family history of bowel cancer?

    Family history changes the plan. One first-degree relative diagnosed under 50, two or more relatives, or a known genetic syndrome (Lynch, FAP) all warrant earlier and more frequent screening - often starting at 40 or ten years before the youngest affected relative.

  • When should I see a GP urgently instead of screening?

    Rectal bleeding, iron-deficiency anaemia, a change in bowel habit lasting more than six weeks, unintentional weight loss or a palpable mass are two-week-wait symptoms - the pathway is urgent diagnostic assessment, not screening.

Sources and further reading

Clinically reviewed against national guidance.

Reviewed by Pulse Atlas Editorial Board (). Published 2026-07-30. Next review 2027-07-30. Reading time ~7 min.

Related tests

Looking for a different test?

In practice, in London

The honest picture around bowel cancer screening in London

With bowel cancer screening, the London question is usually about report turnaround and the radiologist reading it - not whether the scan is available. The wait for bowel cancer screening on the NHS depends heavily on where you live and how urgently the referral is graded. Central and West London private clinics can normally book within a week, with imaging or a procedure slot to follow shortly after. It’s worth being honest about the reason for going private: usually it’s time, not a fundamentally different test.

In practice, a private bowel cancer screening appointment in London means a named consultant, a proper hour in the room (or the equivalent on a video call), and a report you can actually read. Most of the imaging suites and endoscopy units we use sit within a mile of Harley Street or in Chelsea and Fulham, and turnaround on findings is measured in days, not weeks. For bowel cancer screening specifically, the difference between a routine report and a sub-speciality read is where private care earns its keep.

There are a lot of consultants in London who can technically handle bowel cancer screening. Fewer who do it week in, week out for the exact question you’re bringing. We spend most of our time working out which is which - and being straight when a different test or a different specialist would serve you better. Everything runs to CQC, GMC and Royal College standards; the choice is about fit, not floor.